Hammer arrangement for high-speed printers



HAMMER ARRANGEMENT FOR HIGH-SPEED PRINTERS Filed April 5, 1968 K. J. STALLER A ril 7, 1970 2 Sheets-Sheet 1 m 2% r V. n N m M E EJ /o .m wt Mn 1 A W R 6 4, M K R CD 8 Z N up S TORA GE OF ENERGY RUBSER CUSHION DWELC TIME OWELL TIME HARMONIQ MO 7' I ON HAMMER ARRANGEMENT FOR HIGH-SPEED PRINTERS Filed April 5, 1958 K. J. STALLER April 7, 1970 2 Sheets-Sheet 2 ATTORNEY United States Patent O 3,504,623 HAMMER ARRANGEMENT FOR HIGH-SPEED PRINTERS Karel J. Staller, Rutherford, N.J., assignor to International Telephone and Telegraph Corporation, Nutley, N.J.,

a corporation of Delaware Filed Apr. 3, 1968, Ser. No. 718,603 Int. Cl. B41j 9/00 US. Cl. 101-93 8 Claims ABSTRACT OF THE DISCLOSURE A hammer arrangement is provided for high-speed printers in which the hammer is propelled by an actuator toward a printing base, and means are included for stopping said actuator and for storing the kinetic energy of said actuator, whereby said actuator rebounds and collides with the hammer producing a shock resulting in the reduction of the dwell time of the hammer.

BACKGROUND OF THE INVENTION In general this application is related to a hammer arrangement for high-speed printers, and more particularly to high-speed printers printing on-the-fiy, wherein the dwell time of the hammer on the printing plane is minimum.

The general requirement for modern highspeed printers is to print as many characters in a second as possible, and this means a high cyclic rate. This cyclic rate is usually limited by the forces needed to accelerate the moving parts, for example, large spring forces and high specific pressures, and consequently a reduction in the life of the part. High-speed on-the-fly printers are in danger of smudging letters or numbers because of the long dwell time of the hammer, or other elements, which press the layers of paper and carbons to the platen, cylinder, or chain carrying the type character.

There are existing arrangements which try to overcome these inherent problems by providing a cushion arrangement for the hammer. This, however, does not reduce the dwell time sufliciently and only allows the hammer to follow a sinusoidal harmonic motion of a moving part striking an elastic surface. The invention, however, is believed to be an improvement over the existing methods in that a shock created by the collision of two moving parts reduces the dwell time as compared to that of the existing system.

SUMMARY OF THE INVENTION It is an object of this invention to provide an arrangement for a high-speed printer which reduces the dwell time of the hammer.

Another object of this invention is to provide an arrangement in which an actuating member and a hammer collide to produce a shock between the parts and thereby reduce the dwell time normally required by the hammer which is pushed back by elastic forces only.

A feature of this invention is that a means is provided for stopping the actuator and for storing the energy in order to rebound the actuator and cause a collision with the hammer after its impact on the printing base.

According to the broader aspects of the invention, there is provided a hammer arrangement which is propelled toward a printing base by an actuator which has been activated by an energy device, and means are included for stopping the actuator and for storing the energy of the motion of the actuator, such that it is rebounded to collide with the hammer after the hammer had impacted the printing base. This collision causes the dwell time at the printing base to be reduced by shock since the normal harmonic motion dwell time has been interrupted. The hammer and actuator are positioned so that the free distance travel of the hammer, prior to impact on the printing base, is greater than the free travel distance of the actuator prior to its being stopped by the stopping arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more clearly understood with reference to the accompanying description taken in conjunction with the following drawings in which:

FIGURE 1 illustrates an embodiment according to the invention FIGURES 2A through 2C are diagrams useful in describing advantages of an arrangement according to F IG- URE 1;

FIGURE 3 illustrates another embodiment of the invention; and

FIGURE 4 shows still another embodiment employing the principles of the invention as illustrated in FIG- URES 1, 2 and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, hammer 1 is shown having a recessed portion 1a and a mass M1 which is movable in a direction indicated by arrow 5. The hammer is resiliently mounted to a mounting member 6 by means of beryllium springs 7 contained within a resilient material 8 in the hammer. The hammers recessed portion 1a is adapted to engage the part 2a of an L-shaped actuator 2 having a mass M2, the actuator 2 is pivotably mounted at its elbow by pin 9 on the mounting member 6. A resilient cushion 4 is fixed in member 6 and positioned as shown to stop the movement of actuator 2 during its movement in the direction 5. The mass M1 of the hammer is accelerated by the actuator 2 when the lower portion 10 of actuator 2 is attracted by electromagnet 3. The masses M1 and M2 now move together along a gap defined by the letter G until a leading portion of actuator 2 strikes the shock absorbing resilient cushion 4 which may be a rubber cushion, this cushion will stop the movement of mass M2 only, since the gap defined by letter A between the actuator and the rubber cushion is smaller than the gap G which exists between the surfaces indicated as F1 and F2 respectively. The actuator will be stopped and the kinetic energy of the mass M2 will be stored in the rubber cushion 4 by compressing the cushion a distance C.

The hammer continues to move freely along the distance corresponding to gap G until it strikes the printing base 11 which may be a character and platen and squeezes the copies 12 between the hammer, and the character. At this point, the character is rebounded by rubber cushion 4 which was compressed the distance C. A collision occurs between surfaces F1 and P2 of the hammer and actuator because the hammer is at the base 11 when the actuator 2 is being rebounded in the opposite direction to cause the collision between surfaces F1, F2. The resulting shock causes a sharper return motion of the hammer than the harmonic motion return of the hammer that is normally utilized in existing high-speed printers.

This will be more fully understood by reference to the diagrams shown in FIGURES 2A through 2C. In FIGURES 2A, there is shown the force which is created in the electromagnet by a current impulse. FIGURE 2 illustrates the acceleration of the masses M-1 (dotted line) and F2 (solid line) by the attraction of the electromagnet until it reaches the surface of cushion 4, at which point, a compression of the rubber begins corresponding to distance C of FIGURE 1 takes place to store the energy as indicated by curve. The curve would normally continue as indicated, however, at point R the collison occurs between the faces of the actuator and hammer which return the hammer immediately to the zero potential line with the actuator as indicated in FIG. 2B. FIG. 2C compares the use of the cushion arrangement according to existing devices with the arrangement of the invention. The normal dwell time of an existing hammer hitting a rubber cushion is illustrated by curve B which follows the normal harmonic sinusoidal curve for any moving object which strikes a resilient surface, whereas according to curve N the point R which collision occurs creates a shock which will cause the rebouncing period dwell time as indicated by the curves to be less than half the required dwell time of existing arrangements. This is a very important feature which may be used with any of the high-speed printers, such as chain belt printers, drum printing arrangements, or carousel type printers in which the characters are rotating about a vertical axis and must be individually selected to print.

In FIGURE 1, an adjusting feature 13 which may be a threaded screw as shown is utilized to control the position of actuator 2 with respect to the electromagnet 3 and the rubber cushion 4. A turning of the threaded screw toward the electromagnet will move the actuator so as to decrease the distance A and also decrease the distance between the electromagnet 3 and lower portion 10 of the actuator 2 in a well-known manner.

Referring now to FIGURE 3, a drum 14 is shown traveling in the direction indicated by arrow 15. Since this arrangement is similar to the arrangement shown in FIGURE 1, like components are indicated by like numerals. In this arrangement the means for stopping and storing the energy of the actuator is cushion 4 which is now located between electromagnets 3 and attached to an additional adjusting feature 16 which may be threaded as shown for independently adjusting the gap A between the actuator lower portion 10 and the base of rubber cushion 4. Turning of the adjusting feature 16 may move the cushion 4 toward or away from the lower portion 10. In addition, a turning of the threaded screw 13 may move the actuator toward or away from the cushion 4 so as to provide two means of adjusting the gaps shown. As in the previous arrangement, the hammer 1 and actuator 2 are accelerated by the attraction of the electromagnet 3. Both the hammer and the actuator move forward until the lower portion 10 of actuator 2 is stopped by the cushion 4 which absorbs the inertial energy M2 of the actuator 2 and rebounces the actuator in the opposite direction of arrow 5. The ham mer 1, however, continues to move freely along a distance corresponding to the gap G. The rubber cushion 4 stored the energy as the hammer traveled along during compression distance C. The rebounding actuator surface F2 collides with the hammer surface F1 at a point in space corresponding to point R as indicated in FIGURES 2B and C. This causes a much shorter dwell time of the hammer against the printing drum 14 and a much sharper back motion of the hammer than the harmonic motion used in existing arrangements.

FIGURE 4 shows another arrangement utilizing the same principles. In this case, the arrangement 17 is a rotating carriage of characters 17a, also termed a carousel type printer, which is rotating in a direction indicated by the arrow 18. One type of such a printer is described in U.S. Patent No. 3,417,847. It is a requirement of this type of printer that a character 17a be selected and propelled toward the axis of rotation via a guide 19, and then utilizing its propelled momentum to print on a record medium. According to the arrange ment, an electromagnet housing 20 contains coil 21, guidance sleeve 31, and positioned within the electromagnet is actuator 22 having a mass M2. Actuator 22 is composed of two parts, a lower portion 23 within a nonmagnetic cap 30, and a terminal portion 24. Excitation of the coil 21 causes the lower portion 23 to be drawn up against the edge 20a of housing 20 in normal magnetic plugger type fashion. Portion 24 is enclosed within the cushion housing 25 containing rubber cushion 26. The portion 27 of actuator 22 contacts a hammer 28 having the shown mass M1, the hammer is retained in a neutral position by a spring 29. As indicated in the FIGURE 3, the corresponding gaps to those shown in FIGURES 1 and 3 are labeled G, A, and C. Acceleration of mass M2 is limited by the gap A which is smaller than gap G which allows the hammer 28 to propel itself to strike the type bar of arrangement 17. The terminal portion 24 of actuator 2 is stopped by rubber cushion 26 which is then compressed by an amount C. This causes the rebounding of actuator 2, and results in a collision between surfaces F1 and F2. This collision causes a sharper backward motion of the hammer permitting faster rotation and selection of the characters to be printed, and eliminates the possibility of inter ference of the moving characters with the hammer.

These high-speed printing arrangements described above in connection with FIGURES l, 3 and 4 comprise a hammer which is propelled by an actuator toward a printing base in response to a pulsed electromagnet. Interposed in the direction of travel of the actuator, however, is a means for stopping and storing the kinetic energy of the actuator in order to rebound the actuator and cause a collision between the actuator and the ham mer. This collision reduces the dwell time of the hammer at the printing base as has been illustrated in FIGURE 20. The arrangement requires that the hammer and actuator be positioned relative to each other so that the free travel distance of the hammer, prior to impact on the printing base, is greater than the permissible travel distance of the actuator prior to its being stopped. The actuator is stopped by a rubber cushion which is positioned to absorb the kinetic energy of the actuator and reverse the direction of motion of the actuator, thereby, causing the collision between the parts and the reduction of dwell time of the hammer.

I claim:

1. A hammer arrangement comprising:

a hammer positioned for being propelled in a first direction toward a printing base, said hammer having a collision surface (F1) and a propelling surface other than said surface (F1);

an actuator having a collision surface (F2), said actuator being adapted and positioned to propel said hammer in said first direction at said propelling surface, and said surface (F2) being positioned opposite said surface (F1) at a given contact gap (G) from said surface (F1);

means for imparting motion to said actuator so that said actuator moves and propels said hammer in said first direction;

a resilient cushion for stopping the motion of said actuator in said first direction, said cushion positioned from said actuator a given distance (A) smaller than said gap (G), and said resilient cushion to absorb and reflect the inertial of said actuator so as to rebound said actuator in a second direction opposite to said first di rection; and

said hammer after impacting said printing base collides with said rebounding actuator at sur faces F1, F2, whereby due to the collision between the actuator and hammer, the normal dwell time of said hammer on said printing base is effectively reduced.

2. An arrangement according to claim 1 wherein said hammer is flexibly attached to a mounting member and actuator is pivotably attached to said mounting member, and said means for imparting motion is a pulsed electromagnet which causes said actuator to pivot and contact said propelling surface on said hammer so as to impart the propelling motion in said first direction.

3. An arrangement according to claim 2 wherein said mounting member has fixed therein said resilient cushion which is positioned so as to stop the motion of said actuator in said first direction, and said cushion is compressed by the inertial energy of said actuator to cause subsequent rebounding of said actuator in said second direction.

4. An arrangement according to claim 3 wherein said actuator is an L-shaped member which is pivotably attached at its elbow to said mounting member, said L- shaped member having one leg adapted for engaging said electromagnet, and said hammer having a recessed portion adapted to engage the other leg of said actuator; and wherein said mounting member includes a means for adjusting the position of said actuator relative to said electromagnet and cushion.

5. An arrangement according to claim 2 wherein said resilient cushion is fixed within the electromagnet structure so that the motion of said actuator, in response to excitation of said electromagnet, is inhibited and its inertial energy compresses said cushion to cause the subsequent rebounding of said actuator.

6. An arrangement according to claim 5 wherein said actuator is an L-shaped member pivotably mounted at its elbow to said mounting member, one leg of said L- shaped member being adapted for engaging with said electromagnet and cushion, and said hammer having a recessed portion adapter to engage the other leg of said actuator; and wherein said mounting member includes means for adjusting the relative distance between said actuator and said electromagnet and cushion.

7. An arrangement according to claim 1 wherein said means for imparting motion to said actuator is an electromagnet comprising a magnetic housing (20), a coil (21), and a guidance sleeve (31), said actuator being positioned and mounted for movement within said sleeve (31) and including a lower portion (23) and a terminal portion (24), a cushion housing (25) containing said resilient cushion encloses said terminal portion (24), said portion (23) of said actuator forms the armature of said electromagnet, so that in response to excitation of the magnetic coils, said actuator propels towards said hammer towards said printing base, and said actuator at its terminal ortion contacts said resilient cushion which inhibits further travel of said actuator and causes subsequent rebounding of said actuator.

8. An arrangement according to claim 7 including a spring (29) contained within said housing (25) and adapted to retain said hammer in a neutral position, whereby said spring is compressed during propelling of said actuator and hammer towards said printing base.

References Cited UNITED STATES PATENTS 2,787,210 4/1957 Shepard 101-93 2,874,634 2/1959 Hense 10193 3,110,250 11/1963 Fradkin 10193 3,144,821 8/1964 Drejza 10193 3,145,650 8/1964 Wright 10193 3,166,010 1/1965 Fradkin 101-93 3,183,830 5/1965 Fisher et al 10193 3,188,946 6/1965 Schacht 10193 3,200,739 8/1965 Antonucci 101-93 3,266,419 8/1966 Erpel et al. 10193 WILLIAM B. PENN, Primary Examiner 

